Pushbutton switch assembly with flashover protection delay slider means



Jan. 17, 1967 s. A. WOODWARD 3,299,223

PUSHBUTTON swrrcn ASSEMBLY WITH FLASHOVER PROTECTION DELAY SLIDER MEANSFiled April 27, 1966 5 Sheets-Sheet 1 INVENTOR. Stewart A. Woodward BY 2Qduf Attorney- Jan. 17, 1967 s. A. WOODWARD 3,299,223

PUSHBUTTON SWITCH ASSEMBLY WITH FLASHOVER PROTECTION DELAY SLIDER MEANS3 Sheets-Sheet 2 Filed April 27, 1966 Inventor: Stem/a 2*! 14. Woodwardby fljfl y @M Jan. 17, 1967 s. A. WOODWARD 3,299,223 PUSHBUTTON SWITCHASSEMBLY WITH FLASHOVER PROTECTION DELAY SLIDER MEANS Filed April 27,1966 s Sheets-Sheet s :J L38 //4 LIfjf :Z

" Y//////////Al m 2, 1/0 INVENTOR.

2 8 209 Stewart A M/aodwa rd Attorney.

United States Patent Ofifice 3,299,223 Patented Jan. 17, 1967 3,299,223PUSHBUTTON SWITCH ASSEMBLY WITH FLASH- OVER PROTECTION DELAY SLIDERMEANS Stewart A. Woodward, Stratford, ConlL, assignor to GeneralElectric Company, a corporation of New York Filed Apr. 27, 1966, Ser.No. 545,619 13 Claims. (Cl. 200-5) This invention relates generally toelectrical switch assemblies, and particularly to multiple pushbuttonswitch assemblies of the type utilizing slider elements therein forelectrical contact through the assembly. More specifically, thisinvention relates to an improved pushbutton slider type of electricalswitch assembly wherein undesirable occurrences of switch flashover orshorting is prevented.

Pushbutton slider switch assemblies have obtained widespread use forcontrolling various appliances such as ranges, dryers, air conditionersand the like. It has been found that pushbutton slider type switchassemblies, while extremely useful, present a continuing problem offlashover, or shorting between switch means in the assembly whenever theswitch assembly is connected across two or more lines.

This problem of flashover has been recognized in the past. In prior arttime delay switch assemblies, the transfer time, or time betweenbreaking contact in a first switch element and making contact in asecond is entirely dependent upon the speed of depressing the push rod.A quick depression of the pushbutton may therefore result in the switchassembly flashing over. While such prior art switch assemblies aresatisfactory for many applications where the switch assemblies haverelatively high internal mechanical resistance, and the voltage andcurrents through the switch elements are relatively low, it has beenfound that it does not correct the flashover problem in all types ofapplications. Thus, in switch assemblies having unusually low mechanicalresistance, and carrying relatively high currents, the flashover problem still persists. There is, therefore, a need for a pushbutton sliderswitch assembly that will provide a more effective solution to theflashover problem.

It is a general object of the invention to provide an improved switchassembly of the multiple pushbutton slider type.

Another object of the present invention is to provide an electricalslider type switch assembly wherein the switch flashover is minimized.

It is a further object of the present invention to provide a multiplepushbutton slider type switch assembly that achieves an adequate timedelay between breaking and making electrical contact so as to preventoccurrences of flashover during operation of the switch elements.

In carrying out this invention in one form, I have provided an improvedpushbutton switch assembly having a main slider of insulating materialuseful for controlling the opening and closing of movable contact bladesor switch elements in response to actuation of pushbutton rods. I alsoprovide, in this exemplification of my invention, a first auxiliaryslider of insulating material to operate as a time delay element foreliminating flashover or shorting when switching between pairs of switchelements carrying line voltages. The auxiliary slider is normally biasedinto a neutral or non-obstructing position by a biasing coil spring, theauxiliary slider being actuated substantiallysimultaneously withactuation of the main slider by any of the push rods.

The main slider is movable in response to actuation or depression of apush rod to a position which allows one or more contact blades to closewhile causing other of the contact blades to open. The auxiliary sliderincludes cam means along one longitudinal edge which obstructs the oneor more contact blades while the push rod is depressed and prevents theone or more contact blades from closing. The auxiliary slider is movableby the push rod against the force of the spring to this obstructingposition. When the push rod is released, the spring automatically forcesthe auxiliary slider back to the nonobstructing position, allowing theone or more contact blades to close. With the improved auxiliary sliderarrangement an additional step is introduced in the operation of theswitch to provide an extra time delay between breaking and makingcontact and thereby prevent flashover.

In accordance with another aspect of my invention, I provide a secondauxiliary slider which permits the main and first mentioned auxiliarysliders to be manufactured to looser tolerances. The second auxiliaryslider is movable in response to actuation of a push rod at a later timethan the main slider and first auxiliary slider, thereby momentarilydelaying the actuation of the one or more contact blades and allowingthe first auxiliary slider to move to obstructing position so as toensure that the one or more contact blades do not close until the pushrod is released.

In accordance with a further aspect of my invention, I provide amodified form of the above first auxiliary slider. This modified firstauxiliary slider has similar cam means for obstructing the switchelements as the above-described embodiment of the invention. However, Ihave provided a modified biasing spring arrangement.

The subject matter which I regard as my invention is set forth in theappended claims. The invention itself, however, together with furtherobjects and advantages thereof may be understood by referring to thefollowing description taken in connection with the accompanying drawingsin which:

FIGURE 1 is a side elevation of the switch assembly with parts brokenaway illustrating the slider and push rod configuration;

FIGURE 2 is a bottom plan view of the switch assem bly illustrated inFIGURE 1 with the back plate removed;

FIGURE 3 is a layout drawing showing the configuration of the severalsliders of the switch assembly in a first switching position and theirrelation to the movable contact blades or switch elements and the pushrods;

FIGURES 4-6 illustrate in layout form the sequencing of the sliders asthe switch assembly is switched between first and second positions foroperating the circuit of FIGURE 7;

FIGURE 7 is a schematic diagram of a circuit with which the switchassembly of FIGURES 1 and 2 may be used;and

FIGURE 8 is a layout drawing showing a modified embodiment of the firstauxiliary slider illustrated in FIG- URES 1-6 above.

Referring now more particularly to the accompanying drawings in whichlike numerals indicate like parts throughout the several views, I haveidentified the switch assembly embodying one form of the inventiongenerally by the reference numeral 10. Switch assembly 10 comprises ahollow elongate housing 12 formed of suitable molded insulatingmaterial, thehousing including a top wall 14, and a base section 16. Thehollow housing 12 defines therein a longitudinally extending sliderchamber 18, the chamber being completed by a back plate 20 of suitableinsulating material which is removably mounted in an opening 22 in thebase section 16. Detailed features of the housing 12 are more fullydescribed in Patent No. 3,127,482 granted to Hutt and my previous PatentNo. 3,169,173.

The slider chamber 18 has a plurality of slider elements generallydenoted by reference numeral 24 therein. These sliders are elongate andof relatively thin insulating material extending through the chamber andmovable lengthwise or longitudinally in the housing. More specifically,in this exemplification of the invention, three sliders, 26, 28, and 30are slidably mounted in the chamber 18, each being somewhat shorter thanthe chamber for reciprocal movement therein. Each of the slidersincludes several depending leg portions 32 thereon for engagement withthe back plate 20 so as to enable the sliders to be retained in thehousing in all positions while still all-owing the sliders to move inthe chamber 18. Further, as will be observed in FIGURE 2, the sliderchamber 18 is of appropriate width for holding the three slider elementsso as to eliminate any undue lateral play therebetween, while stillallowing the sliders to move in the chamber.

The top wall 14 of the housing 12 includes suitableopenings 34 thereinfor receiving push rods 36 and 38. It will be appreciated that in theillustrated exemplification of the invention, a switch assembly havingtwo push rods is shown, but that any desired number of push rods may beincluded in accordance with the desired application of the assembly.However, as will become apparent hereinafter, the specific embodiment ofmy invention is particularly adaptable for use with a small switchassembly, i.e., one having as few as two push rods, and as few as onemain slider. In a small switch assembly the internal mechanicalresistance or drag is relatively low, and conventional time delayarrangements which depend on this internal mechanical resistance havenot been proven to be satisfactory in small switch assemblies.

The push rods 36 and 38 have the usual pushbuttons 4t) and 41respectively mounted on the upper ends thereof for enabling actuation ofthe push rods vertically through the openings 34. Further, each push rodincludes an enlarged rounded end portion 42 and 43 respectively on thebottom thereof, the rounded end portions being slidably received invertically extending slots or tracks 44 in the housing for facilitatinguse of the push rods.

A plurality of terminal tabs 46, 48, 50, 52, 54, and 56 are mounted inthe switch housing. The terminal tabs 46, 48, and 50 have associatedtherewith movable contact blades or switch elements 58, 60, and 62respectively, the blades being supported from the tabs and extendingacross switch housing in cantilever fashion, as illustrated in FIGURE 2.Similarly, the terminal tabs 52, 54, and 56 have associated therewithfixed contacts 64, .66, and 68 respectively. Thus, corresponding fixedand movable contacts provide electrical switch means for controlling theoperation of various circuits by means of the switch assembly. Further,as will be appreciated by viewing FIGURE 1, the terminal tabs extenddownwardly from the bottom of the switch housing, the tabs 46 and 50being line terminals and the tabs 52 and 56 being load terminals. Inaccordance with the particular application of this switch, to bedescribed hereinafter, the terminal tab 48 is connected to terminal tab46, and the terminal tab 54 is effectively connected to terminal tab 52.

Referring now to FIGURE 3 in conjunction with FIG- URES 1 and 2, theparticular configuration of the sliders 26, 28, and 30 may beappreciated. Each ofthe sliders 26, 28, and 30 includes means forcontacting the push rods 36 and 38 in the form of a guide portion in theupper longitudinal edge thereof, denoted by reference numerals 70 and71, respectively. Further, each of the sliders includes means forcamming the contact blades 58, 60, and 62 in the form of notches cut outof the lower longitudinal edge thereof and denoted by reference numerals72 and 73 and 75 respectively. At the outset, it should be understoodthat slider 28 is the main slider element, i.e., the slider elementwhich has as its primary function the control of movable contact blades.58, 60 and 62 so as to ultimately control the circuit and thus the 4appliance with which the switch assembly is used. This main sliderelement 28 in this exemplification of the invention is designed tocontrol the particular circuit illustrated in FIGURE 7.

Each of the guide portions and 71 in the upper longitudinal edge ofslider element 28 has an oppositely inclined push rod engaging edge 74and 76, respectively. The slider 28 is adapted, by means of these edges74 and 76, to be moved in opposite directions between first and secondpositions in the chamber upon actuation by the two push rods 36 and 38.The purpose of moving the slider 28 between these positions is tocontrol the position of the contact blades 58, 60 and 62. In thisregard, the cam means 72 and 75 are designed to close the blades 58 and62 and the cam means 73 to open the blade 60 when the slider is in theposition illustrated in FIGURE 3. This position is achieved bydepressing of push rods 38. It will be appreciated that the switchassembly 10 may be operated with only the main slider element 28.Obviously the contact blades 58, 60 and 62 can be controlled by the useof this slider alone. Howeved, flashover may occur if only the mainslider element 28 were used in the switch.

The exemplified switch assembly was intended for use in a two line 240volt, alternating current 60 cycle system. The particular bake-broilcircuit illustrated in FIGURE 7 was rated at 13.7 amperes. In such 60cycle systems, it has been found that an arc is often maintained in aswitch means for as long as 8% milliseconds. A positive time delaybetween breaking and closing the contacts of at least 8 /3 millisecondswill therefore usually ensure against flashover.

The slider 26 is characterized as an auxiliary or time delay slidersince its primary function is to prevent flashover. It includes theguide portions 70 and 71, each guide portion having an edge 82 and 83respectively inclined in the same direction. Further, the edges 82 and83 are each recessed from the upper longitudinal edge of the slider by avertical edge 84 and 85 of the guide portions 70 and 71. The slider 26also has means for holding open or obstructing the closing of the guideportions provided in the lower notches 72, 73 and 75. For this purpose,each of the lower notches includes a holding or obstructing portion 86and a second portion 88.

It will also be observed that one of the legs 32 of slider 26, the legdenoted by reference numeral 90, is longer than the others and extendsoutwardly of the housing 12 through an opening 92 in the back plate 20.A coil spring 94 is mounted between the leg and the housing asillustrated in FIGURE 1 having a hook end portion 96 which mounts in thehousing 12 and a ring end 98 which is retained in a notch 100 in leg 90.In this manner, the auxiliary or time delay slider 26 is normally biasedby the coil spring 94 to the left in a neutral non-obstructing position(referring to FIGURES l and 6) for a purpose to be explained more fullyhereinafter.

Referring now to the circuit diagram illustrated in FIG- URE 7, atypical application of the switch assembly 10 in a range will now bemore fully explained. As will be observed from the lower diagrammaticportion of FIG- URE 7, either bake or broil positions may be selected, acircle denoting an open condition of the contact blade and an X denotinga closed condition of the contact blades. In order to correspond withthe view of FIGURE 3, the circuit diagram of FIGURE 7 is illustrated inbroil condition with the contact blades 58 and 62 closed and blade 60open. In this condition, the broil heating elements H and H areconnected in series-parallel relation with bake heating element H acrossthe power supply when switch S is closed. Of course, with the circuit inbake condition, only the bake heating element H is connected across thepower supply.

The flashover problem in the circuit application illustrated in FIGURE 7is particularly severe. A direct short may'result if contact blades 60and 62 are closed or nearly closed at the same time. Referring now toFIGURE 4, the switch assembly as illustrated therein is positioned so asto achieve a bake condition in the circuit. The contact blade 60 isclosed and blades 58 and 62 are opened. The spring 94 has biased theslider 26 back to the left inasmuch as the operator has removed pressurefrom the pushbutton 40 of push rod 36. This movement of slider 26 to theleft or to a nonholding position causes the previously depressed pushrod 36 to raise in the housing as it rides up edge 82.

To transfer to the broil condition, the operator must initially depressthe push rod 38 to the position shown in FIGURE 5. The main slider 28 ismoved to the left as actuator 42 strikes edge 76. The contact blade 66will open as it moves up the camming slope of cam means 73 of slider 28.When the actuator has traversed only vertical portion 85 of guideportion 71, the blade 60 will be fully opened, but arcing between blade66 and fixed contact 66 may occur. As the push rod 38 engages cammingslope 83, it moves delay slider 26 to the right carrying holding means86 under blades 58 and 62.

Also, as the push rod 38 is depressed, blades 58 and 62 are in aposition where they can be closed and place the circuit in the broilcondition. However, before blades 58 and 62 can close, the holding orobstructing means 86 of slider 26 must be moved to the left. As long asthe operator keeps the push rod in the depressed or actuated position ofFIGURE 5, the circuits through switch assembly will remain open.

Upon release of the pushbutton 46 of push rod 38, the spring 94 willautomatically cause the delay slider 26 to return to its normal positionas illustrated in FIGURE 6. Release of the pushbutton 40 will cause theholding means of slider 26 to move to the left thereby permitting theblades 58 and 62 to close and complete the broil circuit as seen inFIGURE 6. It is believed that a number of factors contribute to the timedelay in the closing of blades 58 and 62. These factors include the timeassociated with the depression of the push rod, releasing the externaloperating force from the push rod and the spring return of the slider.It has been found that the extra time provided by the use of my improvedslider arrangement ensures that the arc in one switch means isextinguished prior to closing an adjacent switch means. It will beunderstood that my slider 26 has useful application in larger switchassemblies wherein the currents involved are relatively high.

It will be noted that a second auxiliary or time delay slider 30 ofsomewhat different configuration than time delay slider 26 may be usedin conjunction with slider 26. The guide portions 70 and 71 of thisslider are designed with oppositely inclined push rod engaging orcamming edges 104 and 106 respectively that are recessed away from theupper edge of the slider by vertical portions 105 and 107. With thisconfiguration, the slider 30 will move in response to actuation ofeither push rod 36 or 38 at a later time than the slider 28 is movedthereby as the push rods must move down the vertical portions 105 and107 prior to engaging the camming edges 104 and 106.

The function of slider 30 may best be explained by reference again toFIGURES 4-6. As push rod 38 is depressed, referring to FIGURES 4 and 5,the main slider 28 immediately begins to move to the left. However,slider 30 does not begin to move until the push rod 38 is slightlybeyond the initial position since the edge 186 is recessed, and thecamming portions 108 and 110 of cam means 72 and 75 will hold the blades58 and 66 open until the slider 30 is moved to the right as push rod 38engages edge 106. Thus, slider 30 will prevent actuation to a closedcondition of blades 58 and 62 during the initial travel of slider 28.This is important since, if the guide portions 70 and 71 of slider 26are constructed so that the slider 26 does not move to the right soonenough, or if obstructing portions 86 of slider 26 are too short, it maybe possible for blades 58 and 62 to start closing before slider 26obstructs their closing. The use of the auxiliary slider 30 inconjunction with the time delay slider 26 results in the advantage thatmanufacturing tolerances of sliders 26 and 28 are less critical.

The principle of operation of the switch assembly is similar whenswitching from broil to bake also. Thus, with the push rods 36 and 38and sliders 26, 28 and 30 in their respective positions as illustratedin FIG- URE 6, push rod 36 may be depressed to change back to bakecondition. Depression of push rod 36 will move main slider 26 to theright opening contact blades 58 and 62 and placing blade 60 in aposition where it can be closed. The first auxiliary slider 26 will alsomove to the right, however, since camming slope or edge 82 is inclinedin the same direction as edge 83, and the ob structing means 86 ofslider 26 will pick up and hold blade 60. The slider 30 will move to theleft shortly after push rod 36 is actuated, retaining blade 60 openuntil slider 26 picks it up. ()f course, upon release of pushbutton 4t),spring 94 takes over, moving slider 26 to the left allowing blade 61) toclose.

Referring now to FIGURE 8, a modified embodiment of the above auxiliaryslider 26 is illustrated and is generally denoted by reference numerals126A and 126B. The auxiliary sliders 126A and 126B are both slidablymounted in housing 112 and serve essentially the same function in theswitch assembly as does slider 26, i.e., they provide an extra timedelay between breaking a first contact and closing a second contact.

The auxiliary slider 126A includes notches 172A, 173A and 175A cut outalong the lower longitudinal edge thereof, corresponding to the notches72, 73 and 75 in slider 26. Further, these notches, similarly to thenotches in slider 26, each includes a holding or obstructing portion186A and a second portion 188A. The auxiliary slider 1263 is similarlyprovided with notches 172B, 173B and 175B, each having holding portions186B and second portions 188B.

The slider 126A has an operating slot or guide means A for engaging thepush rod 136 and a clearance slot 171A along the upper longitudinal edgethereof. The slot 170A has a first lower inclined edge 182A and a secondparallel inclined edge 183A. As will be seen from FIGURE 8, depressionor actuation of push rod 136 will cause the slider 126A to slide to theright as the push rod engages edge 182A, and an upward movement of pushrod 136 will cause the slider 126A to slide to the left as the push rodengages edge 183A. However, since clearance slot 171B has no inclinededges, movement of push rod 136 will not move slider 126B. These twopositions of the slider 126A will provide a time delay in the samefashion as described above in relation to the operation of slider 26.Thus, it will be seen that in this modified arrangement, a main slider128 is provided to control the contact blades 158, 160 and 162. When theslider 128 is in the position illustrated in FIG- URE 8, the blades 158and 162 are held open by the camming portions 208 and 210, and the blade160 is ready to be closed upon release of the button 140 of push rod136. The slider 128 also includes guide portions 168 and 169 having theoppositely inclined edges 173 and 175 respectively for engaging the pushrods 136 and 138.

In order to return the slider 126A from an actuated position, a biasingmeans in the form of coil spring 194 is provided. The spring 194 ismounted on push rod 136 and is retained between the upper wall 114 ofthe switch housing and the pushbutton actuator 140 of the push rod 136.The spring 194 acts to normally bias the push rod 136 to an initial orupper position. The spring 194 is compressed upon actuation of the pushrod 136 and at this time the slider 126A is moved to the right or to theobstructing position. Upon release of the push rod 136, the spring 194causes the push rod to raise to the initial position, and the push rodcarries the slider 126A back to the left, or out of obstructingposition.

The slider 126B has its operating and clearance slots 170B and 171B inreverse position than the slots 170A and 171A of slider 126A. Thus, thepush rod 136B will effect movement of slider 126B while not movingslider 126A for delaying the closing of the blades 158 and 162 inaccordance with the operation of my invention. Of course, the push rod138 will also operate main slider 128 in the usual manner. Further, acompression coil spring 195 is mounted on push rod 138 betweenpushbutton 141 and housing wall 114 to raise the push rod, the push rod138 engaging edges 182B and 183B to control the movement of slider 126B.With the modification of the invention illustrated in FIGURE 8, it istherefore possible to provide a time delay during operation of theswitch assembly.

From the foregoing description, it will be apparent that this inventionprovides a novel and improved time delay slider for use in a pushbuttonswitch assembly that minimizes flashover even in extreme switchingapplications. Further, the improved slider arrangement permits thesliders used in the assembly to be manufactured to relatively loosetolerances thereby providing desirable cost reduction of the assembly.It will be understood that the delay slider 26 of this invention can beused to hold open all the blades in the switch assembly as illustrated,or a selected number of the blades and that more than one such delayslider can be used in the assembly.

It will be appreciated, however, that the embodiments which I havedisclosed and described herein are intended for illustrative purposesonly. I therefore intend by the appended claims to cover all suchmodifications that fall within the true spirit and scope of theinvention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A pushbutton switch assembly having a housing, a plurality of movableswitch elements in the housing, at least one main slider in the housing,said main slider having cam means for actuation of said switch elements,a plurality of push rods extending into the housing and engaging saidmain slider for effecting longitudinal movement thereof, said mainslider being movable by one of said push rods for closing at least oneselected switch element and for opening at least one of said switchingelements, an auxiliary slider in said housing, said auxiliary sliderhaving camming means, said auxiliary slider being normally maintained ina first position for permitting actuation of said selected switchelement to a closed condition and being movable to a second positionupon actuation of said one push rod for holding the selected switchelement in an open condition, and means for moving said auxiliary sliderfrom said second position to said first position upon release of saidone push rod to permit the selected switch element to be closed therebyproviding a delay between the closing of the selected switch element andthe opening of at least one of said other switch elements.

2. The switch assembly of claim 1 wherein said auxiliary slider includesguide means for engaging said push rods to move said auxiliary slider tosaid second position upon actuation of any of said push rods, and saidcamming means of said auxiliary slider obstructing the closing of saidselected switch element when said auxiliary slider is moved to saidsecond position.

3. The switch assembly of claim 1 wherein said means for moving saidauxiliary slider comprises spring means engaging said auxiliary sliderand biasing said auxiliary slider to said first position, said auxiliaryslider being moved to said second position against the bias force ofsaid spring means upon actuation of a push rod and returned by saidspring means to said first position upon the release of the actuatedpush rod.

4. The switch assembly of claim 1 wherein said first auxiliary slider isslidably disposed for longitudinal movement in said housing, and asecond auxiliary slider is also disposed in said housing forlongitudinal movement, said second auxiliary slider having cam means forpreventing the actuation to a closed condition of the selected switchelement until said first named auxiliary slider is moved to said secondposition thereby ensuring a delay between closing said selected switchelement and opening the other switch elements.

5. The switch assembly of claim 4 wherein the means for moving saidauxiliary slider includes spring means for biasing said first namedauxiliary slider to said first position when a push rod is released, andupon actuation of a push rod, said first named auxiliary slider is movedto the second position substantially simultaneously as the main sliderelement is moved thereby.

6. The switch assembly of claim 1 wherein said main slider includes apair of oppositely inclined camming edges for engagement by said pushrods, said main slider thereby being movable in opposite directions byalternately depressing one and another of said push rods, said auxiliaryslider having a pair of camming edges inclined in the same direction andengageable with said push rods to move said auxiliary slider in onedirection.

7. The switch assembly of claim 1 wherein the means for moving saidauxiliary slider includes spring means for biasing said one of said pushrods to an initial position, said auxiliary slider including guide meansfor engaging said one of said push rods to move said auxiliary slider tosaid second position against the bias force of said spring means uponactuation of said one of said push rods, and said spring means biasingsaid one of said push rods to said initial position and said auxiliaryslider to said first position, said camming means of said auxiliaryslider obstructing the closing of said selected switch element when saidauxiliary slide-r is moved to the second position.

8. In a pushbutton switch assembly including a housing defining a sliderchamber therein, a plurality of electrical switch means in the chamber,each including a movable switch element, at least one slider disposed insaid slider chamber and actuable by push rods to open and close selectedones of said electrical switch means, a time delay slider disposed insaid slider chamber and movable by depression of one of said push rodsto a hold position for delaying the closing of at least one of saidelectrical switch means for a predetermined time by holding at least oneof said movable switch elements in an open condition, said time delayslider being moved out of said hold position when the depressed push rodis released thereby to close said at least one of said electrical switchmeans.

9. The switch of claim 8 including spring means disposed between thetime delay slider and said housing for normally biasing said time delayslider out of said hold position, said time delay slider having cammeans disposed for engagement with a push rod for holding at least oneof said switch elements in an open condition when a push rod isdepressed, and said spring means urging said time delay slider out ofsaid hold position when the push rod is released to allow said at leastone of the switch elements to close.

10. In a pushbutton switch assembly including a housing, a plurality ofelectrical switches in the housing, at least one main slider elementslidably disposed in the housing and movable therein by push rods toclose at least one of said electrical switches, at least two delaysliders in the housing for delaying the closing of said at least oneelectrical switch, a first of said delay sliders being normallymaintained in an initial position, said first delay slider being movedto a hold position upon actuation of a push rod and being moved back tosaid initial position only upon release of the actuated push rod, saidfirst delay slider including obstructing means thereon for preventingactuation of said at least one electrical switch when in said holdposition whereby an electrical circuit through the switch assembly canbe completed only when the first delay slider is in said initialposition, the second of said delay sliders having camming means forpreventing the actuation of said one electrical switch until the firstdelay slider is moved to said hold position thereby ensuring a delaybetween opening one or more of said electrical switch means and closingsaid at least one electrical switch.

11. The push-button switch assembly of claim including a spring meansdisposed between said first delay slider and said housing for normallybiasing said first delay slider in said first position.

12. The pushbutton switch assembly of claim 10 including spring meansdisposed between the push rods and the housing for normally biasing thepush rods into an initial position, said first delay slider includingfirst guide means for engaging at least one of the push rods wherebydepression of said at least one push rod will move said first delayslider to said hold position, and said first delay slider includingsecond guide means for engaging said at least one push rod whereby saidspring means biases said at least one push rod to return said firstdelay slider to said initial position.

13. A pushbutton switch assembly having a housing, a plurality ofmovable switch elements in the housing, at least one main slider in thehousing, said main slider having cam means for actuation of said switchelements, a plurality of push rods extending into the housing andengaging said main slider for effecting longitudinal movement thereof,said main slider "being movable by one of said push rods for closing atleast one selected switch element and for opening at least one of saidswitch elements, and said main slider being movable by another of saidpush rods for closing said one of said switch elements and opening saidselected switch element, a pair of auxiliary sliders in said housing,each of said auxiliary sliders having camming means, one of saidauxiliary sliders being normally maintained in a first position forpermitting actuation of said selected switch element to a closedcondition and being movable to a second position upon actuation of saidone of said pus-h rods for holding the selected switch element in anopen condition, the other of said auxiliary sliders being normallymaintained in a first position for permitting actuation of said one ofsaid switch elements to a closed condition and being movable to a secondposition upon actuation of said another push rod for holding the one ofsaid switch elements in an open condition, first spring means forbiasing said one of said push rods to an initial position, said oneauxiliary slider including guide means for engaging said one of saidpush rods to move said one auxiliary slider to said second positionagainst the bias force of said first spring means upon actuation of saidone of said push rods, said other of said auxiliary sliders includingguide means for engaging said another push rod to move said other ofsaid auxiliary sliders to said second position against the bias force ofsaid second spring means upon actuation of said another push rod, thecamming means of said one auxiliary slider obstructing the closing ofsaid selected switch element when said one auxiliary slider is moved tothe second position, and the camming means of said other of saidauxiliary sliders obstructing the closing of said one of said switchelements when said other of said auxiliary sliders is moved to thesecond position.

No references cited.

ROBERT K. SCHAEFER, Primary Examiner.

J. R. SCOTT, Assistant Examiner.

1. A PUSHBUTTON SWITCH ASSEMBLY HAVING A HOUSING, A PLURALITY OF MOVABLESWITCH ELEMENTS IN THE HOUSING, AT LEAST ONE MAIN SLIDER IN THE HOUSING,SAID MAIN SLIDER HAVING CAM MEANS FOR ACTUATION OF SAID SWITCH ELEMENTS,A PLURALITY OF PUSH RODS EXTENDING INTO THE HOUSING AND ENGAGING SAIDMAIN SLIDER FOR EFFECTING LONGITUDINAL MOVEMENT THEREOF, SAID MAINSLIDER BEING MOVABLE BY ONE OF SAID PUSH RODS FOR CLOSING AT LEAST ONESELECTED SWITCH ELEMENT AND FOR OPENING AT LEAST ONE OF SAID SWITCHINGELEMENTS, AN AUXILIARY SLIDER IN SAID HOUSING, SAID AUXILIARY SLIDERHAVING CAMMING MEANS, SAID AUXILIARY SLIDER BEING NORMALLY MAINTAINED INA FIRST POSITION FOR PERMITTING ACTUATION OF SAID SELECTED SWITCHELEMENT TO A CLOSED CON-